Effects of nondensifying inclusions on the densification and microstructure of zinc oxide matrix composites

The densification and microstructure development of ZnO containing Zn₇Sb₂O₁₂, ZrO₂, and aggregated ZnO were investigated to elucidate the effect of nondensifying inclusions on the sintering of ceramic/ceramic composites. The inclusion retarded the densification, and the degree of retardation was found to depend on the chemical species of inclusion; Zn₇Sb₂O₁₂ had the largest effect, followed by ZrO₂ and then aggregated ZnO last. The experimental results for aggregated ZnO was explained by the theory which predicts the generation of backstresses. The backstresses give a less significant effect on the densification. For Zn₇Sb₂O₁₂ and ZrO₂, the microstructure of the matrix varied with distance from an inclusion particle; much porosity was observed in the region surrounding the inclusion. Circumferential voids, which are responsible for the suppression of densification, form during the initial stage of sintering. Inclusion particles generate an anchoring effect which retards the densification of the matrix immediately surrounding the inclusion particle during the intermediate stage.Supported by the Inamori Foundation.     

Analysis of proliferative activity using anti-proliferating cell nuclear antigen antibody in gastric cancer tissue specimens obtained by endoscopic biopsy

BACKGROUND: Proliferative activities of tumors are thought to be prognostic features of malignant tumors, but their value as measured by proliferating cell nuclear antigen (PCNA) labeling remains unclear in gastric cancer. METHODS: PCNA labeling rates (LR) were quantified in 121 paraffin-embedded biopsy specimens from primary tumors by immunocytochemistry. RESULTS: Immunohistochemical analyses have demonstrated that PCNA presents an intense staining in the nuclei of tumor cells and mucous neck cells of gastric glands. The PCNA LR ranged from 12% to 79% (mean +/- standard deviation), and a significant correlation was found between bromodeoxyuridine labeling indices and PCNA LR: PCNA LR were closely associated with tumor size, serosal invasion, and nodal involvement. The patients with tumors with high PCNA LR (greater than 40%) were dead significantly earlier than were those with tumors with low PCNA LR: When the PCNA LR and all the clinicopathologic parameters were entered into a Cox regression model, PCNA LR emerged as an independent prognostic factor. CONCLUSION: These results indicate that PCNA LR may be a potentially useful prognostic factor for gastric cancer.     

Human body detection in wet snowpack by an FM-CW radar

An FM-CW radar system was applied to detect a human body buried in a very wet snowpack. This radar uses the L-band microwave frequency with a maximum output power of 100 mW, and utilizes digital signal processing techniques. Field experiments were carried out to detect and map a human body embedded at a depth of 125 cm in a natural snowpack. The radar is shown to have a potential ability to detect avalanche victims, indicating that it may become a tool for snow rescuer operations     

On the loading criteria in the theory of plasticity

The conventional loading criterion in the theory of plasticity becomes ambiguous when it is applied to materials that exhibit straining softening. For instance, it can not differentiate the softening behavior from the unloading process. On the other hand, the loading criterion proposed recently by Qu and Yin is free from such problems, and is more suitable for a general elasto-plastic analysis by finite element method. In the first part of this paper the proposed loading criterion is first reviewed and discussed to highlight the difficulties associated with the inequality conditions used in the conventional as well as the proposed loading criteria. This paper then proceeds to discuss the proposed criterion and reveals its implications. Although the proposed inequality conditions are not generally known in the field, it is found that they are essential and significant in the theory of plasticity.     

Stereoscopic synthesized brain-surface imaging with MR angiography for localization of a peripheral mycotic aneurysm: case report

A patient with subacute bacterial endocarditis and a peripheral mycotic aneurysm is presented. We used a combined multi-slice surface anatomy scanning (SAS) and contrast-enhanced MR angiography image to determine the exact location of the small lesion by applying a skin marker on the scalp and visualizing the relationship of the marker to the brain surface structures and to the lesion. This technique was useful for the removal of a small peripheral aneurysm using only a limited craniotomy.     

Applications of the 4×4 determinant method and the POLYGON ENGINE

In the first half of the paper, various types of processing pertaining to a polygon, using the 4×4 determinant theories are explained along with a new containment test algorithm of a point in a polygon. In the latter half of the paper, a general-purpose geometric processor, the POLYGON ENGINE, is presented which can deal with various types of interference problems, such as Boolean operations in solid modelling, hidden line and surface eliminations, ray tracing and so on. It is, a successor of the TRIANGLE PROCESSOR and is also based upon the 4×4 determinant theories [4–6]. While the TRIANGLE PROCESSOR processes a triangulated polygon on a triangle-by-triangle basis, the POLYGON ENGINE can treat a polygon without triangulation. The latter is expected to be more functional, more efficient and easier to use.     

The new two-dimensional electron gas base HBT (2DEG-HBT):two-dimensional numerical simulation

The bipolar/FET characteristics of the 2DEG-HBT are analyzed extensively by a two-dimensional numerical simulator based on a drift-diffusion model. For bipolar operations at high collector current densities, it is confirmed that the cutoff frequency f_T is determined mainly by the collector transit time of holes and by the charging time of the extrinsic base-collector capacitance C _bc^EXT. The charging times of the emitter and base regions and the base transit time are shown to be negligible. A high cutoff frequency F_T (88 GHz) and current gain h_FE (760) are obtained for an emitter size of 1×10 μm², and undoped collector thickness of 150 nm, and a collector current density J_c of 10⁵ A/cm². The FET operation of the same 2DEG-HBT structure shows a threshold voltage V_th of 0.74 V, the transconductance G_m^max of 80 mS/mm, and maximum cutoff frequency F_T^max of 15 GHz. The dependence of the device performance on material parameters is analyzed extensively from a device design point of view     

Scientific Screening of Raw Diamond for an Ultraprecision Cutting Tool with High Durability

The wide scattering in tool life of natural mono-crystalline diamond tools is considered to depend on intrinsic crystalline defects due to nitrogen impurities in raw diamond. In this paper, the correlation was investigated between the amounts and types of the impurity evaluated by infrared absorption (IRA) and the crater wear and chipping resistances. As a result, diamonds including less total amount of impurity show larger wear resistance and that with larger amount of B2-aggregates show larger chipping resistance. This suggests that the inspection by IRA can be a useful method for screening of raw diamond for highly durable cutting tools.